Insulated wire



Dec. 1, 1931. I H, Bows 1,834,376

INSULATED WIRE Filed June 20, 192

hire/flanlien/7J6 507/72;

rubber,

through a solution of sodium silicate or what.

Patented D... 1, 1931 UNITED STATES PATENT ornca mm 36171176, 01' NEW YORK, N. Y, ABSIGNdB TO WESTERN ELECTRIC 001mm. UGOBEOBATED, 0] NEW YORK, N. Y A. CORPORATION 01 new tom:

INSULATED WIRE Application fled Jane 80, 1924. Serial 80. 721,870.

This invention relates to electrically insulated wire and articularly to improvements in so-called fl dme-proof electrically-insulated wire.

The object of the invention is to provide a flame-proof insulated wire which will be highly efficient in service and economical in manufacture.

A feature of the invention is a wire having an insulating covering, such as rubber, rubber-containing materials or enamel, and a coating of sodium silicate or commercial water-glass applied thereon.

A further feature is a wire having an insulating covering, a coating of sodium silicate or water-glass applied over the insulating covering and an exterior textile covering.

A further feature is a wire having an Insulating covering, a coating of sodium silicate or water-glass applied on the insulating ering. and an exterior covering of proofed cotton.

A further feature is a wire having a rubber-insulation covering, a coating comprising a mixture of sodium silicate or waterglass and glycerine or the equivalent applied thereon, and an exterior covering comprising flame-proofed cotton.

I The single figure shows an insulated wire embodying one form of the invention.

ame-

Referring to the figure, the insulated wire comprises a core 1 of electrically conducting material, a coating 2 of rubber or other insulating material ap lied over the core, a second coating 3 of ame-proof material, such as sodium silicate or water glass, applied over the insulating coating 2, and an exterior textile covering 4, such as braided cotton or flame-proofed cotton, applied over the flameproof coating 3.

One wa of producing the flame-proof insulated wire embodyin the invention is to pass a wire of electrica ly-conducting material having an insulation covering such as rubber compounds, or enamel,

is known commercially as water-glass, the solution being of the proper consistency to give the required thickness of coating. The wire may be drawn through the solution in COV- any suitable manner, but, preferably, should be drawn out of the solution in a vertical direction so as to obtain a coatin of uniform thickness around the wire. en the wire is withdrawn from the solution, after a short interval of drying, 5 or 6 minutes is sufiicient, the material will be set so that a uniform coating 3 of the dried sodium silicate or water-glass will be obtained on the rubbercovered wire. The flexibility and adherence of the coating will be suflicient so that the wire may be reeled or so thatit will stand the customary amount of handling in the braiding process to follow.

If desired, a more flexible and more adhes ve coating may be obtained without materially decreasing its flame-proofing qualities by adding about 10 per cent of glycerine or the equivalent to the solution of sodium silicate or water-glass through which the rubber-covered wire is drawn.

The flame-proof coating of sodium silicate, water-glass or mixtures of those materials with glycerine, may be further rotected from abrasion and vibration by app ying an outer textile coverin 4, preferably cotton or cotton braid, over it by any of the processes wellknown in the art. An additional flame-proof and water-proof protection may be obtained by impregnating the textile fabric with any suitable ame-proofing material, for example, sodium magnesium borate.

If desired, the textile serving 4 may be applied before the water glass coating has dried, so that the coating in. its liquid or partially set condition is taken up to some extent by the serving. -In-either case the water lass is effectively prevented by the serving om flaking off or from being rubbed off or otherwise lost or displaced from handling or bending of the wire. A ractically continuous coating of the water g ass is thus maintained over the insulation coating.

The product obtained by the above-de-,

cient flame-proof conductor. In fact, it has been found that if wire constructed in this manner is held in a fire of sufliciently intense heat until the insulation is burning briskly, 5 upon removal of the source of the heat, the

flame will almost immediately die down.

Such wire has a practical application as ju-mger wire used in distributmg'frames in telep one central stations. However, it is not restricted to such use, but may be used in any other situation where flame-proofing is necessary.

What is claimed is:

1. An insulated wire comprising a core of electricall conducting material having a coating 0! rubber insulating material, a second coating of sodium silicate ap lied im-- mediately over said first-mentione coating, and a cotton covering impre ated with 30 flame-proofing material applie over said coating of sodium silicate.

2. A fiame-proofed insulated conductor comprising a rubber-insulated wire, a coating of water-glass appliedimmediately there- 35 over, and a textile serving applied over the water-glass of sufliciently close texture and fit, to hold the water-glass in place during use of the wire.

3. A wire having an electrical insulation of rubber, a flameroof insulation of dried water-glass applie immediately over the rubber, and a mechanical insulation of closely woven cotton over the dried water-glass.

' 4. An insulated wire comprising a core of 35 electrically conducting material having a coating of rubber insulating material applied immediately thereover, a second coatmg containing sodium silicate and glycerine applied over said coating of rubber insulating material, and a cotton covering impre ated with flame-proofing material appli over said second coating.

5. An insulated wire comprising a core of electrically conducting material having a 45 coating of rubber insulating material applied immediately thereover, a second coating containing water-glass and glycerine applied over said coating of rubber insulation, and a flame-proofed cotton serving over the whole.

In witness whereof, I hereunto subscribe my name this 20th day of June, A. D. 1924.

HENRIK BOVING. 

